Navigator constructor

const Navigator({Key key, String initialRoute, @required RouteFactory onGenerateRoute, RouteFactory onUnknownRoute, List<NavigatorObserver> observers: const [] })

Creates a widget that maintains a stack-based history of child widgets.

The onGenerateRoute argument must not be null.

Implementation 

const Navigator({
  Key key,
  this.initialRoute,
  @required this.onGenerateRoute,
  this.onUnknownRoute,
  this.observers = const <NavigatorObserver>[]
}) : assert(onGenerateRoute != null),
     super(key: key);